Liquid Purification System

Abstract

A liquid purification system includes a filter system having a set of filters with a feed stream, a concentrate stream, and a permeate stream. The feed stream constitutes an input to the liquid purification system. The liquid purification system also includes an electrodialysis system having at least one stack of at least one pair of electrodes, between which is disposed at least one cell pair having an anion exchange membrane and a cation exchange membrane. The electrodialysis system includes a diluate inlet, a diluate outlet and a concentrate outlet. The diluate inlet is fluidly coupled to the concentrate stream and at least a portion of the diluate outlet is fluidly coupled to at least a portion of the permeate stream to produce a purified output stream. A ratio of electrical conductivity of the purified output stream to the feed stream is no less than about 0.55.

1 . A liquid purification system comprising:
 a filter system having a set of filters with a feed stream, a concentrate stream, and a permeate stream, wherein the feed stream constitutes an input to the liquid purification system; and   an electrodialysis system having at least one stack of at least one pair of electrodes, between which is disposed at least one cell pair having an anion exchange membrane and a cation exchange membrane, the electrodialysis system having a diluate inlet, a diluate outlet and a concentrate outlet, wherein the diluate inlet is fluidly coupled to the concentrate stream and at least a portion of the diluate outlet is fluidly coupled to at least a portion of the permeate stream to produce a purified output stream,   wherein a ratio of electrical conductivity of the purified output stream to the feed stream is no less than about 0.55.   
     
     
         2 . The liquid purification system according to  claim 1 , wherein a ratio of electrical conductivity of the concentrate stream to the electrical conductivity of the feed stream is no greater than a factor of 2. 
     
     
         3 . The liquid purification system according to  claim 1 , wherein the electrodialysis system further includes an ion exchange resin between the anion exchange membrane and the cation exchange membrane. 
     
     
         4 . The liquid purification system according to  claim 1 , wherein the filter system is a reverse osmosis system. 
     
     
         5 . The liquid purification system according to  claim 1 , wherein the filter system is a nanofiltration system. 
     
     
         6 . The liquid purification system according to  claim 1 , wherein a filter within the set of filters includes a reverse osmosis membrane. 
     
     
         7 . The liquid purification system according to  claim 1 , wherein a filter within the set of filters includes a nanofiltration membrane. 
     
     
         8 . The liquid purification system according to  claim 1 , wherein a filter within the set of filters has a rejection of sodium chloride of no greater than about 90% using standard brackish water test conditions. 
     
     
         9 . A method of operating a liquid purification system, the method comprising:
 providing a filter system having a set of filters with a feed stream, a concentrate stream, and a permeate stream, wherein the feed stream constitutes an input to the liquid purification system;   providing an electrodialysis system having a diluate inlet, a diluate outlet and a concentrate outlet, wherein the diluate inlet is fluidly coupled to the concentrate stream and at least a portion of the diluate outlet is fluidly coupled to at least a portion of the permeate stream to produce a purified output stream; and   operating the filter system and the electrodialysis system so that a ratio of electrical conductivity of the purified output stream to the feed stream is no less than about 0.55.   
     
     
         10 . The method of  claim 9 , wherein the electrodialysis system includes at least one stack of at least one pair of electrodes, between which is disposed at least one cell pair having an anion exchange membrane and a cation exchange membrane. 
     
     
         11 . The method of  claim 10 , wherein the electrodialysis system further includes an ion exchange resin between the anion exchange membrane and the cation exchange membrane. 
     
     
         12 . The method of  claim 9 , wherein the filter system is a reverse osmosis system. 
     
     
         13 . The method of  claim 9 , wherein the filter system is a nanofiltration system. 
     
     
         14 . The method of  claim 9 , further comprising operating the filter system so that a ratio of electrical conductivity of the concentrate stream to the electrical conductivity of the feed stream is no greater than a factor of 2. 
     
     
         15 . The liquid purification system according to  claim 2 , wherein the electrodialysis system further includes an ion exchange resin between the anion exchange membrane and the cation exchange membrane. 
     
     
         16 . The liquid purification system according to  claim 2 , wherein the filter system is a reverse osmosis system. 
     
     
         17 . The liquid purification system according to  claim 2 , wherein the filter system is a nanofiltration system. 
     
     
         18 . The liquid purification system according to  claim 2 , wherein a filter within the set of filters includes a reverse osmosis membrane. 
     
     
         19 . The liquid purification system according to  claim 2 , wherein a filter within the set of filters includes a nanofiltration membrane. 
     
     
         20 . The liquid purification system according to  claim 2 , wherein a filter within the set of filters has a rejection of sodium chloride of no greater than about 90% using standard brackish water test conditions.